For the purposes of the present invention the term "spacecraft" is intended to encompass a wide variety of manned and unmanned space vehicles including, but not limited to vehicles for manned space travel, satellites, space stations, vehicles for deployment and recovery of satellites, etc.
The term "space debris" as used in this specification is intended as a broad term encompassing dead or inactive satellites, sections of space vehicle launching equipment, small fragments and components jettisoned from spacecraft and launching equipment, all of which having maintained orbital velocity. The term "space debris" includes all objects large and small which have been placed in orbit by space related activities of any kind and which are desired to be eliminated from orbit.
Human exploration of space, deployment of different satellites, vehicles, missiles and research laboratories and utilization of the non-gravitational force feature of space for product experimentation have been in progression for almost three and one-half decades by the United States, Commonwealth of Independent States (CIS), formerly the Soviet Union (USSR), France, Germany, China, Japan, Israel and some other countries since the Soviet Union deployed its first satellite "Sputnik" on Oct. 4, 1957. As space activities occur, a variety of unneeded objects, some large, many quite small, all typically referred to as "space debris" can remain in orbit for extended periods of time. As the result of space activities thus far, the number of orbiting objects, i.e., in lower Earth orbit (LEO) and geosynchronous Earth orbit (GEO) as well as the orbital zone between the LEO and GEO has been rapidly growing. The accumulation of space debris is creating more and more of a hazard and threat to spacecraft or satellites, space shuttles orbit during maneuvers in lower Earth orbit missions. The presence of space debris also compromises the safety of astronauts, especially during EVA activities that will be required for future construction of the Freedom Space Station. According to the current paper of Thomas E. Albert and William B. Margopoulos (IAA90-568) "if actions to minimize the generation of debris are not globally implemented, portions of the LEO region may become unacceptably hazardous for some missions within a few decades." In the same paper it is also mentioned "A math model has been developed to predict the effects of active removal as management option on the future catastrophic collision hazard to spacecraft." Today the leading European Aerospace countries as well as Japan are beginning to focus on the topic. It is inevitable that the space environment must be continuously cleaned to minimize the amount of space debris that can possibly collide with spacecraft and space stations that will be launched within the next few years. It is especially important, before further significant space activities take place that the international space community provide for efficient removal of space debris from the orbital zones that are frequently used for the launching and orbital activities of spacecraft.
Tremendous kinetic energy is generated during hypersonic flight of spacecraft which increases the aerodynamic heating values of the spacecraft. In the past three decades, research scientists have concentrated spacecraft design efforts on study of thermal protection systems. For example, an ablator was developed for use during the Apollo program for protection of spacecraft returning from the moon to Earth in the late 1960's and early 1970's) during their entry into the Earth's atmosphere. Later, thermal protection tiles were developed for the thermal protection of the reusable Orbiter during its hypersonic flight. If the thermal protection system either type of spacecraft was removed or inadequately designed, the spacecraft would be vaporized or melt due to aerodynamic heating converted from a tremendous kinetic energy build-up during its atmospheric entry.
In the past half century, thousands of space researchers and scientists have studied natural thermophysical and thermochemical phenomenon to continuously improve the design and safety of spacecraft. It has been determined through thermophysical and thermochemical calculations and through actual spacecraft re-entry that the surface temperature of a space vehicle during re-entry can reach 3,000.degree. F. due to heat convection, conduction and radiation the first two terms which are converted from kinetic energy during hypersonic flight. Most of the inventor's work in this field was published in national and international leading thermophysics and heat transfer journals and conference proceedings. For example, the surface temperature of a space shuttle orbiter nose cone increases during re-entry to 2,800.degree. F. when employing reinforcing carbon carbon (RCC) insulation and 3,000.degree. F. at higher catalycity columbium surface. These results were indicated in one of the inventor's papers (First International Conference on Hypersonic Flight in the 21st Century, 1988). One part of the present invention will utilize this thermophysics phenomenon in the disposal of orbital space debris. The National Aeronautics and Space Administration (NASA) of the United States has initiated a study of the issue of space debris that has been generated by man's activities in space since the early 1970's. These studies have covered all aspects of the issue from the development of observation capabilities, through the modeling of the space environment and the characterization of break-up events, laboratory hypervelocity impact testing and the exposure of material in space. NASA also has a special radar, optical and infrared telescopes, GEODESS PALAPA, WESTAR spacecraft to obtain all space debris activities to date. This inventor is prepared to propose a handbook entitled "DEVELOPMENT OF NASA SPACE DEBRIS SAFETY" which will be beneficial internationally as well as for the United States' space programs.
The space debris vehicle system (SDVS) which contains the space debris vehicle (SDV) and various sizes of space debris containers including small space debris receptacles (SDR) and large space debris containers (SDC) and huge space debris holders (SDH). The SDVS may be directly launched to low Earth orbit by rocket or it may be deployed from a space shuttle orbiter to the particular orbit that is desired. Additional power will be required to move the SDV from low Earth orbit to higher orbit or geosynchronous Earth orbit. The SDV on board guidance control subsystem and remote video cameras will connect transmission signals with a ground tracking station, space station, or space shuttle orbiter. The SDV will then be maneuvered to intercept space debris that has been identified and located. After appropriate space debris has been acquired and consolidated, it will be deorbited for re-entry into the Earth's atmosphere. The collected orbiting space debris will be initiated to deorbit from an altitude from about 400,000 feet for atmospheric re-entry. Typically, the power subsystem and perhaps a majority of the space debris vehicle will be separated from the space debris container and will be restored to a suitable orbital zone for subsequent reuse. When its power supply is exhausted, it may also be destroyed by kinetic energy or otherwise removed from the orbital zone of interest. In some cases, the uninsulated space debris vehicle (SDV) and the uninsulated space debris container to which the SDV is attached will be melted or vaporized before the SDV descends to 300,000 feet, after a very short period of reentry. As an example of the tremendous heat that is developed as the result of the kinetic energy of re-entry, it should be born in mind that the giant external fuel tank (ET) which is used to supply fuel to the Orbiter during space shuttle Orbiter ascent is very large, having a length of 153.8 feet and a diameter of 28.5 feet. The ET was separated from the Orbiter at an altitude of approximately 240,000 feet and it was ruptured and became melted to vaporization at approximately 235,000 feet due to kinetic energy in the STS-29 mission. The SDVS will follow a pre-designated entry path, in all probability being the same entry path as was used for the external tank of the Orbiter, which directs any surviving portion of the debris to an area of low population density such as the Indian Ocean.